1. Field of the Invention
The present invention relates generally to computer networks and more specifically relates to a method and apparatus for determining the location of discontinuities in computer network connections.
2. Description of the Related Art
Reliability is paramount in computer networking systems. A primary source of network failure is cable breakage or faulty contacts associated with connectors. FIG. 1 shows a conventional computer networking system, in which a server 10 communicates through a control unit 12 to each of a plurality of workstations 18A-18E. The control unit 12 includes a transmitter 12 and a receiver 14.
Data is transmitted from the server 10 to the transmitter 12 in the control unit 16, which outputs the data on a transmit path 20. The transmit path 20 serially connects each of the plurality of workstations 18A-18E in a daisy chain configuration. Likewise, data is transmitted from one or more of the plurality of workstations 18A-18E on a receive path 22, which serially connects each of the plurality of workstations 18A-18E in a daisy chain configuration to the receiver 14. The receiver 14 then outputs the received data to the server 10.
If there is a break in the transmit path 20 at, for instance, point A, those workstations 18C-18E beyond the break will not receive information from the transmitter 12. Likewise, if there is a break in the receive path at, for instance, point B, those workstations 18A and 18B beyond the break, including the server 10, will not receive information from workstations 18C-18E.
FIG. 2 shows an attempt to solve the problem of finding a break in the network connection. In this solution, the transmit path 24 is coupled to an auxiliary transmit path 28 to form a closed transmit loop. Similarly, a receive path 26 is coupled to an auxiliary receive path 30 to form a closed receive loop. If there are no breaks in the connections, each of the workstations 18A-18E receives information transmitted from the control unit 14 twice—once from the transmit path 24 and once from the auxiliary transmit path 28. Likewise, information is received from both the receive path 26 and the auxiliary receive path 30. However, since both the transmit and receive paths are closed loops, there is a substantial risk of signal collisions, which result in distortion and communication errors.
Accordingly, it is a goal of the system and method in accordance with the present invention to quickly and accurately detect and locate breaks in network connections. It is another goal of the present invention to provide a system and method that will not distort information on the network that may lead to communication errors. It is a further goal of the present invention to provide uninterrupted access to all workstations even when there is a break in the network connections.